1. Field of the Invention
The present invention relates to a flow sensor device to obtain flow characteristics of a fluid flow system, such as a system used in administering a beneficial agent to a patient. Particularly, the present invention is directed to a flow measurement device including first and second pressure sensors in a flow passage to measure a flow of beneficial agent and, optionally, the presence of air in the fluid flow system. The invention also includes a related system and method for obtaining such flow characteristics.
2. Description of Related Art
When administering a predetermined amount of a beneficial agent to a patient over an extended period of time in liquid form, it is beneficial, if not necessary, to obtain and monitor relevant flow characteristics such as flow rates and the presence of air. While methods for obtaining such information have existed for a long time, to date, no reliable low cost systems have been developed for disposable use.
For example, fluid flow measurements within a disposable IV fluid line or similar feed set generally have not been financially and technically viable up to this point in time. Low cost electronic flow sensors have existed for some time, but have to date not presented a viable alternative for solving this problem. Limitations to commercialization of such a device have included inadequate dynamic range of low-cost flow sensor systems and the unacceptable costs of total sensor assembly.
One problem with making flow sensors low cost is in the manufacturing process. Silicon chips typically are wire-bonded to a lead frame that is encapsulated and soldered to a printed circuit board. This configuration requires the manual step of welding wires from the chip to the lead frame, which can result in significant additional manufacturing costs.
Likewise, there has been a long-felt need in the medical field for an economical and reliable system to detect the presence of air in IV lines or other medical feed sets. Typically, the presence of air in a fluid line has been sensed externally to the fluid path using a separate ultrasound or optical sensor that must communicate through the disposable tubing or molded component of the fluid path. The ultrasound approach may be subject to misalignment and other geometry changes that can impact the signal conduction around and through the fluid inside the tubing or other components of the disposable fluid path. The optical approach requires specific molded geometries within the fluid path that are reflective or conductive depending on the presence of air or liquid. These systems are subject to variability in and interfacing to the disposable fluid path. Also, the added cost of this air detection system is an impediment to its widespread adoption.
Thus, there remains a need in the art for a reliable fluid flow detection system that is sufficiently inexpensive to allow use in disposable applications. There is also a continued need for an inexpensive and reliable system to detect the presence of air in fluid systems, such as IV lines and feed sets.